In an ER model which of the following is a multivalued attribute?

The correct answer is Phone number.

Key Points

• In an Entity-Relationship (ER) model, a multivalued attribute is an attribute that can have multiple values for a single entity instance.
  • For example, a person entity can have multiple phone numbers (e.g., a home phone, a work phone, and a mobile phone).
  • Multivalued attributes are typically depicted in an ER diagram using a double oval connected to the entity.
  • The Phone number attribute is multivalued because an individual can have more than one phone number.
  • Other attributes like Name, Sex, and Age are typically single-valued because they have only one value for each entity instance.

Additional Information

• To handle multivalued attributes in a database, they are often normalized by creating a separate table to store the multiple values.
• For instance, a table for Phone numbers could include columns for the Person ID (foreign key) and the Phone number.
• Multivalued attributes can complicate query design and database structure, so normalization is a standard practice to simplify data management.
• Multivalued attributes are important in database design to accurately represent real-world data relationships.